Recently, flat panel displays, such as a liquid crystal display (LCD), a plasma display panel (PDP), and an organic light emitting diode (OLED) have attracted considerable attention.
Glass substrates used to manufacture such flat panel displays are manufactured through a molding process of molding glass molten in a glass smelting furnace in the form of a flat panel and a cutting process of cutting the flat glass panel according to a primary standard. The manufactured glass substrates are transferred to a processing line in which the glass panels are processed. In the processing line, the glass substrates are cut to sizes suitable for the standard of desired flat panel displays, and sharp edges of the glass substrates are ground. Also, quality of the glass substrates manufactured in the processing line is inspected using an inspector to determine whether the glass substrates have defects. If the glass substrates have defects, the glass substrates are destroyed. If the glass substrates have no defects, the glass substrates are shipped as finished products.
Meanwhile, the glass substrates may have defects, such as bubbles, foreign matter, for example stone particles, contamination, scratches, cut chips, and cracks, due to various causes during such a series of molding, cutting and grinding processes of the glass substrates as described above. For this reason, in order to manufacture high-quality flat panel displays, defects of the glass substrates are inspected to sort the glass substrates into good-quality products and defective products, and reasons of defects caused during the manufacturing process are checked and corrected.
Glass substrates are inspected through macrography and optical inspection using a camera and a microscope. Also, the glass substrates are totally inspected, and then some of the inspected glass substrates are sampled so as to secure accuracy and reliability of the inspection.
The macrography to inspect defects of the glass substrates is generally performed at an inspection station installed separately from a transfer line of the glass substrates. An inspector unloads a glass substrate from the transfer line and loads the unloaded glass substrate to the inspection station using a handler, and inspects defects of the glass substrate using a lighting device, such as a fluorescent lamp or a halogen lamp, provided in the inspection station. However, the glass substrate may be scratched or cracked due to physical contact and shock during loading and unloading of the glass substrate using the handler. Also, a lot of time is needed, thereby reducing productivity. In particular, it is increasingly difficult to handle glass substrates due to the increase in size and the decrease in thickness of the glass substrates. For this reason, it takes much time and manpower to inspect the glass substrates.
Consequently, there is a high necessity for a glass sheet cutting device that scans a glass sheet to three-dimensionally check defect positions of the glass sheet in the length direction, the width direction and the thickness direction of the glass sheet during a continuous cutting process and cuts the glass sheet into various kinds of glass substrates, thereby lowering a defect rate, preventing waste, and reducing manufacturing costs.